Method of making a metal sandwich structure panel



y 1965 w. s. EGGERT, JR., ETAL 3,194,047

METHOD OF MAKING A METAL SANDWICH STRUCTURE PANEL Filed April 24, 1962 4Sheets-Sheet 1 MUM MMN 58 5 A 5 4O 5 34 J I v 56 10 ATTORNEY y 13, 1965w. s. EGGERT, JR., ETAL 3,194,047

METHOD OF MAKING A METAL SANDWICH STRUCTURE PANEL Filed April 24, 1962 A4 Sheets-Sheet 2 INVENTORS.

Walter SEggarf, Tr

BY Harry P. Schana, K 32 Arrfiggv y 1965 w. s. EGGERT, JR., ETAL3,194,047

METHOD OF MAKING A METAL SANDWICH STRUCTURE PANEL Filed April 24, 1962 4Sheets-Sheet 3 G o Q G O 0 JUL INVENTORS. Walter SEqgefi. IK- QY Harryfischcme ATTORNEY y 3, 1965 w. s. EGGERT, JR, ETAL 3,194,047

METHOD OF MAKING A METAL SANDWICH STRUCTURE PANEL Filed April 24, 1962 4Sheets-Sheet 4 -L(\ U E i i 5 i 9 9% i \N 3 v :i W ER mm y INVENTORS.alfer SIJ Eggert T fi clrry P chcmg ATTORNEY United States Patent METHODOF MAKING A METAL SANDWICH STRUCTURE PANEL Walter S. Eggert, Jr., andHarry P. Schane, Philadelphia, Pa., assignors to The Budd Company,Philadelphia, Pa, a corporation of Pennsylvania Filed Apr. 24, 1962,Ser. No. 189,887 6 Claims. (Cl. 72-349) This invention relates toforming smooth metal plate into sandwich panel shapes and moreparticularly to a method of deep forming individual shapes into a blankwhile maintaining the size of the blank constant.

Drawing has been defined as a process of cold-forming a flat precutmetal blank into a hollow vessel without excessive wrinkling, thinningor fracturing. Heretofore, when a flat blank was drawn, as by dieforming, a change in its shape was brought about by making the metalflow on a plane approximately parallel to the die face in such a mannerthat its thickness and surface are remained about the same as the blank.Heretofore, drawing has included operations in which metal is pulled ordrawn into suitable containing tools from flat sheets into deep orshallow shapes. Geometrical and analytical methods have been devised todetermine the size of blank necessary to obtain a particular drawn cupor dimple. In normal drawing operations amount of reduction is expressedas the actual percentage reduction in the blank diameter due to drawingor shrinking the original diameter of the blank. The present method ofdeep drawing is performed without changing the blank size, thus themeaning given to percentage reduction heretofore is not applicable.Hereinafter, percentage reduction shall mean the reduction in blankthickness due to elongation and shear forming of the metal.

Plate materials have a fixed value of maximum elongation expressed as apercentage factor which is obtained by testing a specimen of the platein tension until it ruptures. Heretofore, it has been impossible toelongate a specimen by tension die forming beyond the theoretical (oractual) maximum elongation.

Heretofore, adherence to the rule of feeding metal into the area beingdeep formed has created distortions in the metal surrounding the diearea which necessitates redrawing, ironing and trimming operations toeliminate the distortions. These distortions have prevented economicstaging and indexing on the deep drawn shapes. Moreover, deep drawinghas heretofore, been limited to the forming of fiat plates. The presentinvention contemplates a novel method which permits a fiat plate to befirst formed into regular compound curvature shapes and subsequentlydeep drawn in isolated areas to form a curved sandwich structure plate.Sandwich structure plates made from the formed curved and/or flat platesmay be connected by welding to similarly formed plates. Welding createsa cast metal structure which does not draw Well. Very large compoundcurvature shapes may be made by welding after forming to avoid any limitas to size or shape, for the edges of the individual plates in thepresent invention, both before and after deep drawing, maintain theexact dimension.

Therefore, it is a primary object of the present invention to deep drawshapes in isolated areas of a metal plate without distorting theremaining area portions of the metal plate;

It is another primary object of the present invention to deep draw aplurality of formed shapes in a metal plate by staging and index ng onpreviously formed shapes;

It is another object of the present invention to provide a novel methodof deep drawing metal plate.

The above and other objects and advantages of the invention will beapparent from the following description of an exemplary embodimentthereof, reference being made to the accompanying drawings wherein:

FIG. 1 is a perspective view of a sandwich structure plate having deepdrawn dimpled formations therein formed by the present novel method;

FIG. 2 is a section in elevation of the novel staging dies installed ina typical hydraulic press showing the dies in open position;

FIG. 3 is a section in elevation of the novel staging dies of FIG. 2showing the dies in a half-closed position;

FIG. 4 is a section in elevation of the novel staging dies shown inFIGS. 2 and 3 showing the dies in closed position;

FIG. 5 is an enlarged section in elevation of the working portion of thedies shown in FIG. 4;

FIG. 6 is an enlarged detail in section showing the detail of the novellocking bead.

Referring now to the drawings, FIG. 1 shows a metal plate 10 having deepdrawn dimples 12 formed therein. Two metal plates 10 are welded togetherat the mating face of the deep drawn dimples 12 to form a sandwichstructure. It is to be understood that these drawn sandwich plates maybe made from the same set of dies to be described hereinafter, butcompound curvatures having non-symmetric plate structures may require aset of dies for each of the plate structures.

' FIG. 2, by way of a preferred embodiment, illustrates a hydraulicpress having a frame 14 mounted on a concrete super structure 16. Alower cross frame 18 is connected to the frame 14 and provides amounting structure for the lower die plate 20. Connected to the lowerdie plate 20 is a first male forming die 22, here shown to be apreforming punch, and a second forming die 24, here shown to be a finalforming punch. Connected to the concrete super structure is a lowerhydraulic cylinder or cushion ram 26. Affixed to the movable ram 26 ofthe cylinder (not shown) is a floating platen 28 which provides supportfor a plurality of pilot pins 30 which extend through apertures in thelower cross frame 18 and the lower die plate 20 and provide support forthe floating lower die ring 32. Aifixed to the lower die ring 32 is amale gage plug 34; opposite the male gage plug 34 is a spring loadedfemale gage positioner 36 guided in an aperture provided in an upper dieforming ring 38. A female upper preforming die ring or retainer ring 40and a final forming die ring or retainer ring 42 are shown to be formedin the upper die forming ring 38 axially aligned with their respectivemale forming dies 22 and 24. It is to be understood that the die ringsor retainer rings 40 and 42 while shown to be an integral part of theupper die forming ring 38 may be constructed as individual parts mountedin an upper die forming ring 38 and attached to the upper die plate 44.Upper die plate 44 is attached to an upper bolster 46 which is carriedby a vertically movable upper ram 48. Shown inserted between thefloating lower die ring 32 and the upper die forming ring 33 is a metalplate 10 having a deep drawn dimple 12 formed therein indexed over themale gage plug 34. A preformed dimple 50 which has been formed by themale forming die 22 is shown indexed over the male forming die 24 priorto the die structure being closed. It will be understood that the plate10 shown in FIG. 2 has already undergone two complete die formingoperations to be described hereinafter. Floating rollers 52 are providedto aid in feeding the plate 1! into the staging die structure.

Referring now to FIG. 3 wherein the die structure of FIG. 2 is shown ina half closed position. Female gage positioner 36 is seated on thesloping sides of the formed 03 g V dimple .12 at the upper surfaces ofthe metal plate 10,

and-the male gage plug 34 is seated on the sloping'pon' tions of thedimple 12 at the lower surface of the dimple 12. Gage positioner 36 andits associated spring loading means-54*have been'compressed duringthedownward stroke of the upper ram 48 carrying the upper die assembly.Cooperation of plug 34 and .positioner 36 affixes the plate in apredeterminedposition prior to the mating of die ring 32 and die ring38; Die ring 32 has male locking'and' coining beads 56 thereon, and.die'

ring 38 has female locking and'coining grooves 58 therein. 1

These cooperating-locking and coining beads and grooves when employedfor a single stage operation may be varied to some extent as will beexplained later. When the die 38 is moved downwardvertically by the ram48, it. con tactsthe metal. plate 10 and forces it againstthe floatinglower die ring .32.; Male locking beads s represent the highest surfaceof themating die rings. Beads 56 initially contact the plate 10 to coingrooves in the plate. Continned downward movement ofthe ram 48 causesthe possible draw it illustrates that'the dimple 50 is drawn deeperthan'final form and can be final formed by a very slightfiow of materialto the shape of the dimple 12. By

, employing a'preform punch of the preferred-shape it was pilot pins toforce the floating platen 28downward against the ram 269f the hydrauliccylinder provided with a constant pressure device such as a meteringorifice, well known in the hydraulic press art. fice causes the ram 26to exert a constant 'force on the floating platen28 so long as the ram'48 moves'pivot pins 30 downward at a constant velocity. Thus, plate 10is struckand coinedat the area opposite the bead 56and groove 58isolating a blank area inside of the locking bead and groove oppositethe male punch 22. The head and groove also firmly lock to prevent anymovement of metal outside ,of the locking bead and groove. As the ram 48is continued to be lowered, the

male punch is forced into engagement with the metal plate 10 causing themetal opposite the male punch 22 to' The metering oridiscovered thatdeeper shapes could be obtained than with two drawing stages.

groove 58 is shown in, FIG. 6; The distance .from the A detail of thenoveli'coining andlocking bead 56 and top of the male locking1bead.56 tothe ibottomof the female locking groove 58 is made approximately 30%less than the distance between the face of the die ring 32 .and the faceof the, die ring 38. V Itzwas discovered that the die ring 38 pressesthe plate ltllupon thel bead 56 andthins the metal between the bead andthe groove 56,

58 causing the-metalto flow outward from the bead and groove. 'The-plate-thickness adjacent to the. bead and groove was formed thickerthan the remainder of the plate. When a substantial pressure wasexerted'upon the upper die ring 38, the pressure was concentrated at Ithe coining bead and groove and the adjacent material be wrapped aroundand; formed by said, male punch;

Simultaneouslyduring the forming operation by male punch 22, themaleepunch 24'is being forced into the preformed dimple SOand causes thepreformed dimple to-be stretched over the male punch 24 to take theexact "shape of the 'finalfforming punch 24. As already ex plained withregard to male punch 22, locking beads 56 and grooves 58 prevent anyflow of metal outside of the area encompassed by the locking beads. Ram48 con-. tinues downward until die ring 32"finally touches against thelower dieplate-20 mounted onthe lower cross frame 18. This terminatesthe downward movement of the ram '48 and causes a rapid increase in'thehydraulic pressure which is actuating ram 48. As is well known in thehydraulic press art, a reversing switch, not shown,

may be tripped by a critical pressure indicative of this plate 10 formedby the male punch 22 is formed into die ring 40 which has a largerdiameter than the male punch 22. a portion of unrestrained metal betweenthe die ring 40 and the punch 22. rounded nose which is deeper than thedie 24 as indicated by the dotted line 60. Also the' nose of the die 22is more narrow than the nose of the final formed 'die '24. In

the novel method of staging with a preforming punch 22- and finalforming punch 24. the preformed dimple is actually drawn to a deeperdepth than required for the final form. When the final forming punch 24isdriven into the preformed dimple 50, the nose of themale die'24initiallylrcontacts' the sloping portion of the preformed dimple 50causing the metal at the fiat nose of the-die '24 .to be stretchedoutward and pulled down, into contact with the final forming die 24. Itis to be understood This permits the male punch. to uniformly stretchthereto which has beencaused. to be thickened. The area ofplate'rnaterial encompassedby the beadand groove is heldsub'stantiallyin a locked position by the material which is thickened, and by thelocking bead and groove at thethinned area. Not only. does the novelblocking bead and groove prevent the metal outside the locking bead areafrom being formed, but it'also provides a means whereby the pressureexerted on the upper die forming ring is distributed equally aroundtheclosed perimeter formed by the'bead and groove. Should a plurality ofdies such as those shown inFIGS. 2, 3and 4 be employed tooperate'simultaneously, the pressure imparted to the locking groove.when the die structure is operated,

I wrinkles and distortions vand/or'change the-curvature of It will henoted that die 22 has a the metal plate being so formed.

By way of example, if it is desired torform flatrplate material to beused for the floor of a railway car, the staging dies shown in FIGS. 2,3 and 4 may be employed or a plurality of dies similar to the diesshownin FIGS.

2, 3 and 4 may 'beernployed. A piece of flat plate It) is selectedhaving the-desired outside dimensions of the finished sandwich structureshape. Plate v10 is first fed into the first stage or preformed diesandis locked into position by the coining .and 'lockingjbeads and grooves.A

preforme'd shape is embossed in the plate and thefdies are released. Themetal plate 10 isjadvanced, and preformed shape Sit-is placed oppositethe final forming die 24, A

set. of locking beads 56 and grooves '58 provided on ring 32 and ring 38at the second .stage mayjbe made to the exact dimensions of the lockingbeadand locking grooves I used in the previous'stage, but instead ofcoining a new groove-the locking bead and locking groove, merely fit thethird stage. The third stage is not a forming stage but merely positionsthe plate by forcing a formed dimple over a gage plug 34 having theexact shape as the final forming punch 24. Thus, it can be seen that anindefinite length of plate can be fed into the novel staging dies whichcontinue to locate and position the plate at the first and second stageby positioning on a dimple 12 previously formed at the stages, and willmaintain critical indexing from stage to stage only because the plate isnot distorted.

The metal drawn inside the locking bead and groove is formed as anisolated area where there is no distortion, buckling or wrinkling in thebasic contour or shape of the plate formed. Thus, any shape such ascylinders, spheres or toroids may be made as sandwich structures byfirst forming smooth curved plate sect-ions that are to be weldedtogether to form the desired structure, and then drawing the dimpledshapes in the plate sections without distorting the basic curvature ofthe formed plate. If a fiat rectangular plate is drawn by the presentmethod, the dimpled shapes may be drawn therein without changing theperimeter or edges of the plate, thus, enabling .a plurality of suchplates to be Welded together after they are drawn without the necessityof trimming or reforming the fiat portions of the plate in any way. Anycompound curvature may be imparted to a plate before being die drawn.Drawing is accomplished without distorting or altering the basicperimeter of the formed plate.

While one embodiment of the invention has been described for purposes ofillustration it is to be understood that the novel locking beads andlocking grooves can be employed on other types of forming dies and thatthe sandwich structures may be formed with other shapes of dimples whichmay be formed by either the final forming or preforming dies or both.

What is claimed is:

1. The method of making a metal sandwich structure panel from a sheetmetal blank, said method comprising the steps of positioning the blankbetween a pair of die members, one of said pair of die members having abead projecting outwardly from its face and the other having acomplemental groove to matingly receive the bead therein, subjecting theblank to the closing action of the dies to reduce the thickness of theblank along a line by said bead and groove, said closing action of saiddies causing metal of the blank to flow in opposite directions away fromsaid line to increase the thickness of the blank along immediateadjacent inner and outer margins of said line, the locus of said lineenclosing an area of said blank, clamping said blank at the thickenedmargins of said line with a high degree of pressure and simultaneouslydeforming the enclosed area encompassed by said line whereby thematerial outside of the area being deformed is pre vented from flowinginto the area.

2. The method of making a metal sandwich structure panel from a sheetmetal blank, said panel comprising a plurality of longitudinally-spacedlaterally-extending rows of spaced dimples, each dimple comprising afiat circular end wall and a tapered side wall, said method comprisingthe steps of: intermittently feeding said blank through a preformingstation and a final forming station; preforming rows of laterally-spacedrounded-end dimplelike shapes, at said preforming station, in successiveportions of said blank, each row being preformed by simultaneously colddrawing the metal within laterally-spaced areas to form such shapes andpreventing the flow of metal into such areas and thereby preventdimensional distortion of said blank outside of such areas; and finalforming said rows of said rounded-end dimple-like shapes into saiddimples at said final forming station by simultaneously holding saidblank around said dimple-like shapes of each row as each row passesthrough said final forming station, and stretching said rounded-enddimple-like shapes to form said dimples.

3. The method of claim 2 wherein said preventing is done by coining saidblank around said areas and holding the portions thus coined.

4. The method of claim 3 wherein said coining is accomplished bypressing said blank between upper and lower die members provided withcoining beads and coining grooves between which the metal blank issqueezed.

5. The method of claim 2 wherein said drawing is accomplished bypressing die rings against one side of said blank and rounded-end maledies against the other side of said blank so as to stretch said metalwithin said areas over said male dies and thereby form said rounded-enddimple-like shapes.

6. The method of claim 2 wherein said feeding com prises indexing saidblank to position it in said preforming and final forming stations, bygrasping dimples that have already been formed, immediately prior to anypreforming and final forming steps.

References Cited by the Examiner UNITED STATES PATENTS 1,760,288 5/30Stevens 18*19 1,804,607 5/31 Groehn 11349 1,841,920 1/32 Smith.

1,856,319 5/32 Cooper t1819 1,904,268 4/23 Bronson 18-56 2,190,807 2/40Steinberger 1'856 2,230,189 1/41 Ferngren 18-19 2,254,376 9/47 Lyon.

2,285,903 *6/42 Clark 11349 XR 2,413,591 12/46 Sturdy 11342 2,43 0,43 711/47 Trauvetter.

2,640,402 6/53 Comstock 18-419 XR 2,694,227 11/54 Fordyce et al. 181 9XR 2,967,328 1/61 Shelby et al 1'819 2,989,936 6/61 Farnsworth 1343 XRWILLIAM J. STEPHENSON, Primary Examiner.

2. THE METHOD OF MAKING A METAL SANDWICH STRUCTURE PANEL FROM A SHEETMETAL BLANK, SAID PANEL COMPRISING A PLURALITY OF LINGITUDINALLY-SPACEDLATERALLY-EXTENDING ROWS OF SPACED DIMPLES, EACH DIMPLE COMPRISING AFLAT CIRCULAR END WALL AND A TAPERED SIDE WALL, SAID METHOD COMPRISINGTHE STEPS OF: INTERMITTENTLY FEEDING SAID BLANK THROUGH A PREFORMINGSTATION AND A FINAL FORMING STATION; PREFORMING ROWS OF LATERALLY-SPACEDROUNDED-END DIMPLELIKE SHAPES, AT SAID PREFORMING STATION, IN SUCCESSIVEPORTIONS OF SAID BLANK, EACH ROW BEING PREFORMED BY SIMULTANEOUSLY COLDDRAWING THE METAL WITHIN LATERALLY-SPACED AREAS TO FORM SUCH SHAPES ANDPREVENTING THE FLOW OF METAL INTO SUCH AREAS AND THEREBY PREVENTDIMENSIONAL DISTORTION OF SAID BLANK OUTSIDE OF SUCH AREAS; AND FINALFORMING SAID ROWS OF SAID ROUNDED-END DIMPLE-LIKE SHAPES INTO SAIDDIMPLES AT SAID FINAL FORMING STATION BY SIMULTANEOUSLY HOLDING SAIDBLANK AROUND SAID DIMPLE-LIKE SHAPES OF EACH ROW AS EACH ROW PASSESTHROGH A FINAL FORMING STATION, AND STRETCHING SAID ROUNDED-ENDDIMPLE-LIKE SHAPES TO FORM SAID DIMPLES.